ENS 48333
ENS Event | |
|---|---|
18:00 Sep 21, 2012 | |
| Title | Unanalyzed Condition Identified in Appendix R Fire Scenario |
| Event Description | On September 21, 2012, a condition was identified where hydrogen may become entrained in the charging pump suction after the credited pump is restarted as part of the alternate shutdown procedure for the Auxiliary Building basement and mezzanine levels.
An air operated valve separates the Volume Control Tank (VCT) from the charging pump suction and this valve fails open on loss of air or power caused by the postulated fire. The alternate flow path from the Refueling Water Storage Tank (RWST) fails closed on a loss of air or power. A manual valve is provided to bypass this closed valve. However, due to hydrogen pressure in the VCT and the potential for significant pressure losses in the piping from the RWST to the charging pump suction, insufficient elevation head exists in the RWST to ensure that hydrogen will not become entrained. If this condition is left unmitigated, the credited charging pump is assumed to fail. Due to the location of the postulated fire and its impact on equipment and cables, no other inventory makeup sources are credited. Compensatory Measures have been implemented as follows: 1. All fire detection and suppression systems in the Appendix R fire zones have been verified functional. 2. All Hot Work in the area has been suspended. 3. Continuous Fire Watch has been posted in the Appendix R fire zone. 4. Combustion engine powered vehicles are restricted from entering the Auxiliary Building. 5. Within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> remove all non-attended transient combustible materials from Appendix R fire zones. The NRC Resident Inspector has been notified.
This is a retraction of ENS report 48333 that was submitted at 2028 EDT on Friday, September 21 , 2012. A 10 CFR 50.72(b)(3)(ii)(B) ENS notification was made due to a condition that was identified where hydrogen may become entrained in the charging pump suction after the credited pump is restarted as part of the alternate shutdown procedure in the event of a fire in the Auxiliary Building basement and mezzanine levels. A subsequent engineering evaluation calculated the amount of gas that will be entrained into the charging pump suction flow and the duration of the entrainment. This evaluation demonstrates that for the most limiting Appendix R scenario that the charging pump will entrain a minimal amount of gas for a short duration, and is unaffected by this condition. Inventory control for the reactor coolant system is maintained throughout the scenario. Based on the above information the 'Unanalyzed Condition' ENS notification made on September 21, 2012 is being retracted. The licensee notified the NRC Resident Inspector. Notified R1DO (Bellamy). |
| Where | |
|---|---|
Ginna  New York (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+2.47 h0.103 days <br />0.0147 weeks <br />0.00338 months <br />) | |
| Opened: | Rex Reissner 20:28 Sep 21, 2012 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Sep 28, 2012 |
| 48333 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 499142014-03-13T20:30:00013 March 2014 20:30:00
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